Now that gets me chair dancing!

So we are both 1951 baby boomers. For some reason I was thinking you were about 20 years younger than me. But given how scrambled my memory has been for the past few years, I could easily be thinking of another member.

I soon learned about the 4/4 beat timing of Disco music, and tempo measured in beats per minute BPM. I learned how to combine the two concepts so that the beginning of the new record could be overlaid over the end of the old record, matching the speed and matching the first beat of the new measure with the first beat of the old measure. It's harder to explain on paper than it is in practice.

But, it produces the seamless flow of music.
I know exactly what you're describing as I used to do it when making cassette tapes to play in the car. Makes for an enjoyable ride, especially on long trips.